This invention generally relates to a dilatation catheter suitable for percutaneous transluminal angioplasty procedures which can perfuse blood distally of the dilatation balloon during the inflation thereof.
In typical percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through tee brachial or femoral arteries and advanced therein until the distal tip thereof is in the ostium of the desired coronary artery. A guidewire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced into the patient's coronary vasculature until the distal end thereof crosses the lesion to be dilated and then the dilatation catheter is advanced over the previously introduced guidewire until the di1atation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, relatively inelastic balloon is inflated to predetermined size with radiopaque liquid at relatively high pressures (e.g., greater than 8 atmospheres) to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall to thereby dilate the lumen of the artery. The balloon is then deflated so that the dilatation catheter can be removed and blood flow resumed through the dilated artery.
Further details of angioplasty procedures and the devices used in such procedures can be found in U.S. Pat. Nos. 4,332,254 (Lundquist); 4,323,071 (Simpson-Robert); 4,439,185 Lundquist); 4,468,224 (Enzmann et al.) 4,516,972 (Samson); 4,538,622 (Samson et al.); 4,554,929 (Samson et al.); and 4,616,652 (Simpson) which are hereby incorporated herein in their entirety.
Steerable dilatation catheters with built-in or fixed guidewires or guiding elements are used with greater frequency because the deflated profile of such catheters is generally smaller than conventional dilatation catheters with movable guidewires or elements having the same inflated balloon size. Further details of low-profile steerable, dilatation catheters may be found in U.S. Pat. Nos. 4,582,181 (Samson), 4,619,263 (Frisbie et al.), 4,641,654 (Samson et al.), and 4,664,113 (Frisbie et al.) which are hereby incorporated in its entirety by reference thereto. The lower profile of these catheters allows them to cross tighter lesions and to be advanced much deeper into the patient's coronary anatomy. Moreover, the use of steerable low-profile dilatation catheters shortens considerably the time for the angioplasty procedure because there is no need to first advance a guidewire across a lesion and then slide a conventional dilatation catheter over the previously advanced guidewire to position the balloon thereof across the lesion.
When the balloon is inflated during typical angioplasty procedures, all blood flow through the artery is blocked. While it is widely believed that long term dilation of the stenosis will increase the probability that the stenosis wi11 remain open after dilation and will also reduce the risk of re-stenosis, presently used typical dilation times range from about 15 to 60 seconds because longer periods would result in dangerous ischemic conditions distally of the inflated balloon in a coronary region which may already be in jeopardy.
Efforts have been made to develop dilatation catheters which perfuse blood through the catheter or by the balloon of the catheter when the balloon is inflated during angioplasty procedure in order to avoid ischemic conditions distally of the balloon. For example the dilatation catheters described in U.S. Pat. Nos. 4,581,017 (Sahota) and 4,423,725 (Baran et al.) both describe means to perfuse blood distally when the dilatation balloon is inflated to facilitate longer inflation periods, but unfortunately both dilatation catheters are very complicated structurally and are expensive to manufacture. Additionally, any guidewire utilized with these catheters was disposed in the same lumen through which the blood must flow, thereby reducing the flow, unless the guidewire is withdrawn prior to the dilations to a location proximal to the perfusion inlet holes in the catheter body.
What has been needed and heretofore unavailable is a steerable dilatation catheter which provides for the distal perfusion of blood during angioplasty procedures through a lumen separate from the lumen receiving the guidewire to thereby allow for longer term dilations. The present invention satisfies that need.